Months ago, before awards season truly got underway, most were anticipating a head-to-head matchup between two master filmmakers: Quentin Tarantino’s Once Upon a Time in Hollywood and Martin Scorsese’s The Irishman. Smash cut to January, and these two heavily lauded films may have to settle for Screenplay trophies as a latecomer has crashed the Best Picture party and is now in pole position to take the whole enchilada. Sam Mendes’ World War I film 1917 burst onto the scene in December as a technically marvelous and (for some) awe-inspiring effort. The film plays out entirely …